Conveyor belts of the type described above are often used in air conditioning plants for e.g. quick-freezing or cooking of food products.
Such conveyor belts are usually made up of link means which comprise upward extending lateral plate elements and at least two parallel transverse rods connected thereto. The link means are interconnected in such a manner that the conveyor belt is turnable vertically and laterally.
The lateral plate elements of the link means of the conveyor belt may, however, be designed in various ways. Examples of conveyor belts of the above type having differently designed lateral plate elements are e.g. described in WO87/04136, WO91/04209, EP1714918, U.S. Pat. No. 6,237,750 and U.S. Pat. No. 7,270,231.
Normally each lateral plate element includes an integrally formed outer one-half plate section and an inner one-half plate section. The outer one-half plate section is slightly offset outwardly with respect to the inner one-half plate section thereby enabling the inner one-half plate section on a link means to extend over the inside surface of the outer one-half plate section on the adjacent link means. During operation, the outer one-half plate section on a link means and the inner one-half plate section on an adjacent link means overlap and slide together as the belt moves along its path.
The conveyor belt may be arranged to travel in a straight path until it enters a spiral or helical configuration. When aligned in the helical configuration, the lowermost tier of the conveyor belt is supported by a drive system while each of the remaining tiers is supported by an underlying tier. The interface between adjacent tiers is designed to keep the belt supported and laterally aligned.
During use, an upper edge of the link means in the underlying tier normally contacts the bottom surfaces of the transverse rods of the link means in the overlying tier. The tiers are laterally aligned by resting said upper edge against said transverse rods and by guide tabs arranged on the link means of the overlying tier.
One of the at least two transverse rods of a link means extend through elongated slots formed on lateral plate elements of a neighboring link means to loosely connect the two links means.
When moving in a helical configuration, longitudinally aligned tensile forces are applied to the belt causing it to stretch in the direction of travel. Also, when the belt travels in the helical path, the belt is stacked into circular tiers and stress may be created that may act as a bending force bending the link means. Moreover when the belt is stacked in tiers, the contact surfaces or points between links means in underlying and overlying tiers are gradually worn which may lead to breakage.